Memory: Do animals ever forget?
By Emma Young Read more: “The ultimate guide to memory“ EVERY morning, you take a walk in the park, bringing some bread to feed the pigeons. As the days wear on, you begin to see the birds as individuals; you even start to name them. But what do the pigeons remember of you? Do they think kindly of you as they drop off to sleep at night, or is your face a blank, indistinguishable from the others strolling through the park? These questions may seem whimsical, but knowing what other creatures recall is crucial if we are to understand their inner lives. It turns out that the range of mnemonic feats in the wild is nearly as varied as life itself. If you take memory to mean any ability to store and respond to past events, even the simplest organisms meet the grade. Blobs of slime mould, for instance, which can slowly crawl across a surface, seem to note the timing of changes to their climate, slowing their movement in anticipation of an expected dry spell – even when it never actually arrives. With the emergence of the first neurons about half a billion years ago, memories became more intricate as information could be stored in the patterns of electrical connections within the nervous system (see “The making of a memory“). This type of learning may have been behind the Cambrian explosion – the sudden appearance and rapid evolution of more complex species about 530 million years ago – because it enabled animals to exploit new niches,